Lactobacillus plantarum MB452 enhances the function of the intestinal barrier by increasing the expression levels of genes involved in tight junction formation

Abstract

BackgroundIntestinal barrier function is important for preserving health, as a compromised barrier allows antigen entry and can induce inflammatory diseases. Probiotic bacteria can play a role in enhancing intestinal barrier function; however, the mechanisms are not fully understood. Existing studies have focused on the ability of probiotics to prevent alterations to tight junctions in disease models, and have been restricted to a few tight junction bridging proteins. No studies have previously investigated the effect of probiotic bacteria on healthy intestinal epithelial cell genes involved in the whole tight junction signalling pathway, including those encoding for bridging, plaque and dual location tight junction proteins. Alteration of tight junction signalling in healthy humans is a potential mechanism that could lead to the strengthening of the intestinal barrier, resulting in limiting the ability of antigens to enter the body and potentially triggering undesirable immune responses.ResultsThe effect of Lactobacillus plantarum MB452 on tight junction integrity was determined by measuring trans-epithelial electrical resistance (TEER) across Caco-2 cell layers. L. plantarum MB452 caused a dose-dependent TEER increase across Caco-2 cell monolayers compared to control medium. Gene expression was compared in Caco-2 cells untreated or treated with L. plantarum MB452 for 10 hours. Caco-2 cell RNA was hybridised to human oligonucleotide arrays. Data was analysed using linear models and differently expressed genes were examined using pathway analysis tools. Nineteen tight junction-related genes had altered expression levels in response to L. plantarum MB452 (modified-P < 0.05, fold-change > 1.2), including those encoding occludin and its associated plaque proteins that anchor it to the cytoskeleton. L. plantarum MB452 also caused changes in tubulin and proteasome gene expression levels which may be linked to intestinal barrier function. Caco-2 tight junctions were visualised by fluorescent microscopy of immuno-stained occludin, zona occludens (ZO)-1, ZO-2 and cingulin. Caco-2 cells treated with L. plantarum MB452 had higher intensity fluorescence of each of the four tight junction proteins compared to untreated controls.ConclusionsThis research indicates that enhancing the expression of genes involved in tight junction signalling is a possible mechanism by which L. plantarum MB452 improves intestinal barrier function.

VSL#3 probiotics regulate the intestinal epithelial barrier in�vivo and in vitro via the p38 and ERK signaling pathways

“…Tight junctions are the major determinants of paracellular permeability. Although changes in epithelial tight junction protein expression have been studied extensively in monolayers stimulated by cytokines, challenged by bacteria, or exposed to aspirin (16)(17)(18)(19)(20)(21)(22), much remains to be understood about barrier disruptive changes under inflammatory conditions in vivo. Our results have indicated that the probiotic mixture VSL#3 protects colonic epithelial barrier function in acute DSS colitis, as demonstrated by effective prevention of increased Evans blue dye uptake.…”

Probiotics as regulators of inflammation: A review

“…Of particular interest is the ability of specific probiotic strains to significantly decrease tumor necrosis factor alpha (TNF- a pro-inflammatory cytokine that causes leaky barriers by directly impairing the integrity of the tight junctional complexes between epithelial cells. Other probiotic strains bolster mucosal membrane integrity by directly affecting expression of one or more of the important tight junctional proteins (e.g., zonulin-1, occludin and cingulin) [16,17]. Various other cellular and molecular mechanisms (eg.…”

The Role of Intestinal Barrier Function in Early Life in the Development of Colitis

“…Some probiotic bacteria, such as Lactobacillus plantarum (Anderson et al, 2010a;Anderson et al, 2010b), can improve tight junction integrity (physical barrier). For a recent review see Ulluwishewa et al (2011).…”

“…Analysis shows that probiotics may shorten the duration and severity of diarrhoea, particularly in young children. Some evidence suggests that probiotics may improve intestinal barrier function (Anderson et al, 2010a;Anderson et al, 2010b). This will be discussed further in Section 5.1.…”